1. Field of the Invention
The present invention relates to disc defect management for a write once disc, and more particularly, to a write once disc, a disc drive therefor, and a method of performing disc defect management in consideration of the compatibility with a rewritable disc drive.
2. Description of the Related Art
Disc defect management is the process of rewriting data stored in a user data area of a disc in which a defect exists to a new portion of the disc's data area, thereby compensating for data loss caused by the defect. In general, disc defect management is performed using linear replacement or slipping replacement methods. In the linear replacement method, a user data area in which a defect exists is replaced with a spare data area having no defects. In the slipping replacement method, a user data area with the defect is slipped and the next user data area having no defects is used.
Both linear replacement and slipping replacement methods are, however, applicable only to discs such as a DVD-RAM/RW, on which data can be repeatedly recorded and recording can be performed using a random access method. In other words, the conventional linear replacement and slipping replacement methods cannot be applied to write once discs on which recording is allowed only once. In general, the presence of defects in a disc is detected by recording data on the disc and confirming whether or not data has been recorded correctly on the disc. However, once the data is recorded on a write once disc, it is impossible to overwrite new data and manage defects therein.
After the development of a CD-R and a DVD-R, a high-density write once disc with a recording capacity of several dozen GBs has been introduced. This type of disc can be used as a backup disc since it is not expensive and allows random access that enables fast reading operations. However, disc defect management is not available for write once discs. Therefore, a backup operation may be discontinued when a defective area, i.e., an area where a defect exists, is detected during the backup operation. In general, the backup operation is performed when a system is not frequently used, e.g., at night when a system manager does not operate the system. In this case, it is more likely that the backup operation will be discontinued because a defective area of a write once disc is detected.
Meanwhile, when additional data will not be recorded on a recordable disc, i.e., when only data reproduction will be allowed, write protect information is recorded on the disc to prevent the data recorded on the disc from being mistakenly erased. However, once the write protect information is recorded, recording is not further allowed, and, thus, possible disc defects cannot be managed. Because recording is not allowed in a data area of the disc after recording of the write protect information, disc defect management cannot be performed.
Conventionally, location information regarding disc areas for disc defect management has been specified in the specifications and a disc drive designer designs a disc drive based on the specifications. Accordingly, if a new disc area is further added to the existing disc areas, a conventional disc drive cannot recognize the presence of the new disc area and satisfactorily perform disc defect management.